Shaft seal for furnaces



l l l l l Il kV/ Z N K. M. HALEY ET AL SHAFT SEAL FOR FURNACES Filed Jan. 29, 1952 Sept. 4, 1956 /IIIIA l I l l I I l United States Patent O SHAFT SEAL Fon FURNACES Kenneth M. Haley and Harold V. Trask, Ashland, Ky., assignors to Oglebay, Norton and Company, Cleveland, Ohio, a corporation of Delaware Application January 29, 1952, Serial No. 268,856

6 Claims. (Cl. 286-8) rockable members must obviously be provided with a sealing means to prevent the escape of gas and/or` dust thereabout both for the purpose of protecting the bearings of the shaft or other rotatable member as well as to insure satisfactory and safe operation of the furnace per se. By way of example, vbut without limitation there-` to, shaft furnaces for indurating bodies of linely divided metalliferous materialsare frequently provided with transversely extending breaker rolls or other members which must be rocked or partially rotated from a point exteriorly of the furnace. The seals for the `shafts of the breaker rolls, where they extend through the side walls of the furnace, must be of a nature which can withstand high temperatures, oxidizing gases, and finely divided dust particles, which are abrasive in nature, without hindering the angular movement of the breaker rolls. The conventional shaft seals provided heretofore have not, however, proved adequate to the requirements for sealing rockable members extending through the side walls of a furnace, especially for the ends of breaker rolls in shaft furnaces employed to indurate metalliferous materials,

since such seals rapidly deteriorate with resulting loss of because the operation of the furance must ordinarily bediscontinued during -the replacement operations.

An object of this invention is, therefore, to provide an improved apparatus and composition comprising a gas and dust sealfor angularly rockable or rotatable shafts or members extending through the side walls of a furnace, which seal will `prevent the escape of gases and dustfrom theinterior of the furnace without hampering the movement of the shaft or rotatable member, the seal being capable Aof havingadditional sealing composition added thereto during the operationof the furnace and without the requirement. of dismantling or disassembling operations. L l A Another object of the invention is to provide an improved seal for a rockable or rotatable shaft extending through the side wall of a furnace in which the sealing action is provided by inorganic fibres impregnated with a composition, the major portion of which comprises asphalt and a solvent.

Another object of the invention is to provide an improved gas and dust sealfor an angularly rockable member extending through the side wall of afurnace comprising a housing surrounding the shaft or rockable member in the region thereof extending through the side wall of the furnace, which housing contains a semiplastic, tireresistant packing material with provisions for adding additional quantities of material from a point exteriorly of the furnace without interrupting the operations of the latter.

A further object of the invention is to provide an improved shaft seal of the type defined in the preceding paragraph and in which the housing of the seal is further provided with means productive of heat insulation about a portion of the seal together with means for maintaining in semiplastic or uent condition the additive packing material as it is supplied to the seal.

A still further object of the invention is to provide a gas and dust sealing material for angularly rockable members, which material consists essentially of asbestos libres saturated with a composition comprising essentially graphite, silicates, asphalt, and a solvent.

A more specific object of the invention is to provide an improved gas and dust seal for shafts or other rockable members extending through the side walls of a furnace comprising a housing secured to the furnace wall and surrounding the portion of the member extending through the wall in spaced relationship thereto 'and having the space between the housing and member filled with a semiplastic material which is resistant to high temperatures, oxidizing gases and abrasive particles in the furnace, the said housing being provided with a conduit extending exteriorly of the furnace for the supplying of additional sealing material to said housing with a portion of said conduit being disposed interiorly of the furnace and subjected to at least a part of the heat therein, thereby maintaining the material in the conduit and housing in semiplastic condition.

A further object of the invention is to provide an improved gas and dust seal as defined in the preceding paragraph and further characterized by the provision `of means surrounding a portion of the housing within the furnace for collecting therein fine particles of material and retaining the same as an insulation about the major portion of the inner part of said housing.

The invention also has as an object thereof, an improved gas and dust seal as defined in the two preceding paragraphs and in which the said sealing material cornprises essentially inorganic fibres impregnated with silicates, asphalt and a solvent.

The invention further resides in other novel features of the construction and composition, which features together with further objects and advantages of the invention will be apparent to those skilled in the art to which it pertains from the following description of the presently Y preferred embodiment thereof described in conjunction with the accompanying drawing, in which:

Fig. lis a fragmentary longitudinal sectional View through a portion of a shaft furnace provided with a breaker roll rotatably or rockably supported therein, a

L portion of the roll being broken away and the novel shaft seal and composition being shown partly in section and partly in elevation;

Fig. 2 is a front elevational view of the novel structure of the improved seal shown detached from the furl nace and with the shaft and sealing material removed, a

to be utilized in indurating bodies of finely divided metalliferous material. While the invention is thus disclosed in conjunction with a breaker roll in a shaft furnace, it is to be understood that this is simply to illustrate the manner in which the invention is employed and the severe conditions under which it has been found necessary to provide an efficient seal. The invention is not, however, limited to such use except as may be hereinafter required in the subjoined claims.

in Fig. 1 the numeral 1i) designates generally the shaft of a furnace in which pellets or agglomerates of finely divided metalliferous material are to be heated for effecting induration thereof. This furnace may be of any desired construction, the details of which do not constitute a part of the invention. Extending through the side walls of this furnace are the shaft-like portions 11 and 12 of a breaker roll assembly 13, the outer end portions of which are rockably supported in suitable bearings 14 and 15 mounted upon structural members such as 16, 17 of the furnace framework or supporting structure. The breaker roll here shown comprises a generally tubular portion or portions 18 secured to the shaft-like portions 11 and 12 by suitable headers or end portions 19 thus providing an annular space, such as 20, communicating with passages such as 21 and 22 through the shaft-like portions to enable circulation of a cooling medium. These breaker rolls are adapted to be rocked or angularly oscillated through a suitable linkage 23 connected with a power means not shown. The details of the construction of the breaker rolls and their mode of operation forms no part of this invention, but is disclosed and claimed in the copending application of Ira H. Wynne et al., S. N. 232,686, filed lune 2l, 1951, and assigned to the assignee of this invention.

In accordance with this invention, a gas and dust seal for the rockable or rotatable portions 11 and 12 of the rocker rolls or shafts is provided, where these portions extend through the furnace Walls 24 and 25. Each seal includes a housing supported upon the walls and maintains a composition of inorganic fibres impregnated with a semiplastic, fire-resistant material about the rolls or shafts, provision being made for supplying additional quantities of the sealing material or composition to the housings during operation of the furnace. The seals at either end of a breaker roll or shaft are identical and hence like reference numerals will be applied to like parts of both.

Each seal housing comprises a tubular member 26 which has an internal diameter largerl than the diameter of the shaft-like portion such as 11 of the roll with which it is to be used and a length which is preferably in the order of one to one and one-half times the diameter of the portion 11 of the shaft or rockable member. The tubular member 26 is disposed in an opening provided through the furnace wall, such as 24, and is secured by welding to a mounting plate 27 which extends over the opening through the wall and is rigidly secured to the latter by suitable means, as for example by the bolts 2S and nuts 29 or by other conventional means. The interior of the tubular housing member 26 is closed by a plate 30 having a circular opening of suicient diameter to receive the shaft-like portion which is to be sealed and allow rocking movement of the latter even when heated. The plate 30 is preferably polygonal and extends above and below the tubular housing member 26 for a purpose hereinafter described.

A portion of the tubular housing member 26 extends externally of the furnace and has an annular securing ring or plate 31 welded or otherwise secured thereto. This plate or ring is provided with a plurality of circumferentially spaced openings 32 to facilitate` removably securing a closure member thereto. This closure member has a central opening adapted to fit about the shaft or tubular portion 11 without hindering rocking thereof. As disclosed herein, this closure member is formed in two parts comprising a lower member or plate 33 and an upper member or plate 34 which are provided, respectively, with circumferentially spaced openings 35 and 36 adapted to align with the openings 32 in the securing ring or plate 31 for the reception of mounting bolts, such as 37, to thereby retain the closure member in place. Preferably the two portions of the closure member are suitably supported and detachably secured together on either side of the central opening therethrough as by connecting lugs or plate-like members 3S welded to one of the closure members 33, 34 and bolted to the other of the members by means of bolts 39, and cooperating nuts 40.

From the construction thus described, it will thus be apparent that an annular space is provided about the shaft-like portions, such as 11, 12, of the rocker member or shaft where they extend through the furnace walls. This annular space is adapted to be filled with a fireresistant sealing material which is semiplastic in nature and comprises inorganic fibres impregnated with a material which is semiplastic or substantially liuent when heated. In the preferred embodiment, the inorganic fibres are preferably provided in substantially rope-like form and disposed about the shaft-like portions within the tubular housings 26 in the form of multiple helical convolutions 41, this being effected while the closure members 33, 34 are removed. For example, a rope of asbestos fibers may be thus employed, which fibres are either impregnated with a sealing composition, hereinafter described, prior to their being placed about the shaft-like portions or after they are thus disposed. Any additional spaces within the tubular housings are then filled with the sealing composition and the closure plates 33, 34 are secured to each other by the bolts and nuts 39, 40 and to the housings by the bolts and nuts 37.

This supplying of the additional composition to completely fill the space within the housing 26 may be effected by any suitable means. Preferably, however, the structure is provided with a conduit means for facilitating this supplying of the additional sealing material and to permit the addition of further material of this nature during the operation of the furnace for replacing any which may have been consumed or otherwise lost during operation. For this purpose, the tubular housing member '1 26 has an opening formed adjacent the top thereof in the portion extending within the furnace 10. This opening communicates with an elbow 42 welded or otherwise secured about the opening and extending to and secured in the mounting plate 27, as will be clearly apparent from Fig. 3. Communicating with the elbow 42 is a pipelike extension 43 of the conduit means, the outer end of which is disposed externally of the furnace wall and is closed with a pipe plug 44 or other suitable means. It will be apparent that by removal of the plug 44, additional sealing material may be introduced into the housing 26 through the conduit formed by the pipe 43 and elbow 42. This supplying of material through the conduit may be effected by any suitable apparatus as, for example, by pumps or other equipment utilized for forcing grease and other lubricants into fittings. The provision of the elbow 42 within the furnace enables the heat in the latter to be communicated to the pipe 43, thus maintaining the sealing composition remaining therein and in the elbow 42 in generally fluent condition so that it does not harden or otherwise clog the supply conduit.

Heat insulation is provided for the portion of the shaft seal within the furnace by allowing portions of the finely divided material therein to accumulate and be retained about the housing so that the material within the furnace itself provides the heat insulation. This is effected in accordance with the preferred embodiment by surrounding the tubular housing member 26 with an opentop box-like structure generally designated 4S. Thus, as previously mentioned, the inner closure plate 30 extends both above and below the housing member 26 and is spaced from the inner surface of the adjacent side wall of the furnace thereby providing one side of the said open-top box, the opposite side being provided by plate 27. Between the plate 30 and the adjacent plate 27 are provided a bottom plate member 46 and side plate members 47 and 48 suitably welded or otherwise secured to the closure plate 27 and to the plate or member 30, thus forming a substantially rectangular, open-topped box about the tubular housing 26 in the portion thereof disposed internally of the furnace. Preferably, the upper ends of the side Walls 47 and 48 slope inwardly, as indicated at 49, to facilitate the passage of pellets or other relatively large bodies of material therepast.

It will be apparent that, when the furnace is of the type used for indurating pellets or bodies of finely divided metalliferous material, a portion of that material, which inevitably is present in unpelletized form due to abrasion and other actions within the furnace, will accumulate within the said open-topped box 45 about the inner portion of the shaft seal. This finely divided material, being mineral and of irregular shapes, provides a porous, fire-resistant packing surrounding the inner portion of the housing 26 and tends to insulate that portion of the housing from the direct heat of the furnace, thereby reducing the temperatures to which the shaft sealing compound is subjected. The elbow 42, however, extends slightly above the top of the box 45 so that at least a portion of it is exposed to the heat of the furnace and is not surrounded by the finely divided material accumulating within the box. This is for the aforementioned purpose of maintaining the sealing composition within the pipe 43 and elbow 42 in generally fluent condition, since the elbow will be strongly heated, which heat will be transmitted by conduction along the pipe 43.

As mentioned heretofore, the sealing material within the housing 26 preferably comprises inorganic fibres impregnated with a fire-resistant material `which is normally semiplastic, but which may be fluent under the temperature conditions of the furnace. Without limitation thereto, one suitable type of such sealing material is in the form of asbestos fibres impregnated with asphalt and a solvent. Other materials may be advantageously added, as, for example, graphite and various silicates. By way of specific example, in the preferred embodiment, the portions such as 11, 12 of the tubular member or shaft extending through the side walls of the furnace are first surrounded by a rope of asbestos fibers and the remainder of the space, as well as the rope itself, are filled with a composition having the following analysis:

This composition may be supplied through the conduit formed by the pipe 43 and elbow 42 by a grease gun or grease pump of conventional construction until the pipe 43 is filled, after which the plug 44 is placed in sealing engagement. A shaft'seal of this nature has been successfully employed in a shaft furnace for indurating pellets or other agglomerates of magnetite and provided satisfactory sealing against the gas and dust of the furnace with no appreciable leakage of the gas or dust. Moreover, a satisfactory seal was continuously maintained by the routine supplying of small additional quantities of the sealing composition at intervals of eight hours during continuous operation of the furnace.

Compositions other than those which have the specific analysis set forth above may be employed, although preferably these compositions will comprise, as a major portion thereof, asphalt and a solvent therefor impregnating the inorganic fibres, it being recognized that it is not essential that the fibres be asbestos nor that they be disposed in rope-like helical form about the shaft. The said sealing composition is improved by the addition of graphite and silicates, at least a portion of the latter, for example, being in the form of fibres of asbestos or other inorganic materials. if desired, all the fibres may be supplied in the semiplastic sealing material forced through the pipe 43 and elbow 42. Also, in some instances satisfactory sealing may be effected by inorganic fibres to which has been added a grease of the type which will withstand high temperatures and oxidizing gases.

The novel sealing means is so constructed as to enable the sealing of the shaft to be properly maintained without the necessity of shutting down the furnace and/or dismantling major portions thereof. Thus, as mentioned above, periodic additions of the semiplastic material through the pipe 43 and the elbow 42 will maintain an effective seal for long periods of time. However, if it should be necessary to repaclr the seal, this may be effected by removing the closure members 33, 34 and this does not result in the necessity of dismantling the bearings for the rotatable member nor does replacing the rope-like fibres 41 necessarily require terminating operation of the furnace, since removing the plates 33, 34 does not provide a direct opening into the furnace. Hence, repacking operations may be carried out while the furnace is in operation. Furthermore, the novel construction of the shaft seal provides for maintenance of the sealing composition in substantially fluent condition, while preventing subjecting of the composition and the inorganic fibres to excessive temperatures. Moreover, the shaft sealing structure is provided in the form of an integral unit readily applied to existing furnaces as will be evident from an inspection of Fig. 3, since al1 attachments to the walls of the furnace may be effected exteriorly thereof, as, for example, by substituting welding for the connecting bolts and nuts 28, 29.

It will be apparent from the above detailed description of the present preferred embodiment of the invention that there has been provided a novel structure and sealing composition for effecting sealing of a rockable shaft extending through the side walls of the furnace and which prevents the escape of gas and finely divided dust or other particles thereabout thus protecting the operators of the furnace and the bearings of the shaft from injury or damage. Although a specific embodiment and certain variations thereof have been described in detail, it will be apparent that other alterations and adaptations may be made by those skilled in the art after having had the benefit of this disclosure. Consequently it is to be understood that the invention is not to be considered as limited to the specific details herein illustrated and described except as required by the spirit and scope of the appended claims.

Having thus described the invention, We claim:

l. A gas and dust seal for an angularly rockable meinber extending through the side wall of a furnace comprising a housing surrounding the portion of said member extending through said wall in spaced relationship to said member, a body of fire resistant packing material in the space between the latter member and the walls of said housing, a conduit communicating with said housing interiorly of the furnace and having a portion extending exteriorly of said furnace for supplying additional material therethrough to said housing, and means surrounding the portion of said housing adjacent the inner side wall of the furnace for collecting therein fine particles of material in said furnace and retaining the same as an insulation about the inner portion of said housing, the said conduit interiorly of the furnace having a part extending above said means so as to be subjected to at least a portion of the heat of the furnace thereby preventing hardening of the material in the conduit and housing.

2. A gas and dust seal for an angularly rockable member extending through the side wall of a furnace comprising a housing extending interiorly and exteriorly of the furnace Wall and spacedly surrounding the portion of said member extending through said wall, re resistant sealing material in said housing surrounding said member and filling the space between the latter and the walls of said housing, a conduit communicating with said housing interiorly of the furnace and having a portion extending exteriorly of said furnace for supplying additional seaiing material therethrough to said housing, and means surrounding the portion of said housing adiacent the inner side wall of the furnace for collecting the :in iine particles of material in said furnace and retaining the same as an insulation about the inner portion of said lic-using, the said con-duit interio-rly of the furnace having a part extending above said means so as to be subjected to at least a portion of the heat of the furnace thereby maintaining the material in the conduit and housing in substantially fluent condition.

3. A gas and dust seal for an angularly rockable member extending through the side wall of a furnace comprising a housing secured to the furnace wall and surrounding the portion of said member extending through said Wall in spaced relationship thereto, a lire resistant packing and sealing material in said housing surrounding said member and lling the space between the latter and the wails of said housing, a conduit communicating with said housing and having a portion extending exteriorly of said furnace for supplying additional scaling material therethrough to said housing, and an open topped box interiorly of said furnace and surrounding the portion of said housing adjacent the inner side Wall of the furnace for collecting therein fine particles of material in said furnace and retaining the same as an insulation about the inner portion of said housing, the said conduit having its connection with the said housing interiorly of the furnace with a part of said conduit extending above sai-d box so as to be subjected to at least a portion of the heat of the furnace thereby maintaining the material in the conduit and housing in iiuent condition.

4. A gas and 'dust seal as defined in claim 3 and wherein the said tire resistant material comprises inorganic fibers impregnated with a composition the major portion of which comprises asphalt and a sollvent.

5. A gas and dust seal as delined in claim 3 and Wherein the said iire resistant material comprises asbestos bers helically disposed about the said rockable member and impregnated with a composition comprising essentially graphite, silicates, asphalt and a solvent.

6. A gas and dust seal for an angularly rockable member extending through the side wall of a furnace comprising a mounting plate adapted to be secured to the furnace Wall, a housing secured to said plate and surrounding the portion of said Imember extending through said wall in spaced relationship to said member, the said housing being adapted to contain a semiplastic fire resistant packing material in the space between the member and the walls of said housing, removable closure means for the portieri of said housing exteriorly of said furnace and having an opening therethrough fitting about said member, a conduit communicating with said housing in the region thereof adapted to extend into the furnace and having a portion extending exteriorly of said mounting plate for supplying additional sealing material to said housing when the latter is mounted in the furnace, and an open topped box surrounding the portion of said housing adjacent the inner side wall of the mounting plate and adapted to be disposed in said furnace for collecting tine particles ot material in said furnace and retaining the same as an insulation about the inner portion of said housing, the said conduit having its connection with vthe said housing extending above said box so as to be subjected to at least part of the heat of the furnace so as to maintain the `material in the conduit and housing in iiuent condition.

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